JP6904284B2 - Optical safety sensor - Google Patents

Description

The present invention relates to an optical safety sensor that measures the distance to an object using the TOF method and detects the intrusion of the object into the monitoring area from the change in the distance.

A sensor using a TOF (Time of Flight) method is known, which measures the distance to an object that reflects light by using the time from when light is projected until when the reflected light is received. Further, an optical safety sensor that detects the intrusion of an object into the monitoring area from a change in the distance measurement result by using the TOF method is known (for example, European Patent No. 2315052B). However, in order to meet the safety standard in the optical safety sensor using the TOF method, it is necessary to set a test target. For example, Prior Document 1 includes a reference optical transmitter and a reference receiver for performing a safety-related self-test, in addition to an optical transmitter and a receiver for detecting the intrusion of an object into a monitoring area. Is disclosed.

U.S. Pat. No. 2016 / 0327649A1 (published November 10, 2016)

However, in Patent Document 1, the reference optical transmitter and the reference receiver are configured exclusively for self-testing and are not used for monitoring the monitoring area, which is a factor of high cost. Further, it is conceivable that the optical safety sensor that monitors the monitoring area is simply duplicated without using the reference optical transmitter and the reference receiver dedicated to the self-test. According to this configuration, it is possible to continue monitoring even if any of the sensors fails, but there is a problem that a specific abnormality location cannot be specified when an abnormality occurs.

One aspect of the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to realize an optical safety sensor at low cost.

The present invention employs the following configuration in order to solve the above-mentioned problems.

That is, the optical safety sensor according to one aspect of the present invention includes a plurality of light emitting and receiving devices including a light projecting unit that projects light into the monitoring area and a light receiving unit that receives the reflected light from the monitoring area. A plurality of distance measuring units that measure the distance to an object in the monitoring area using the time required from the light projection to the light reception, and the plurality of distance measuring units based on the measurement results by the distance measuring unit. A plurality of detection units for detecting an abnormality occurring in any of the light receivers are provided, and one light emitting / receiving device forms one pair with a corresponding distance measuring unit and one detection unit. Each of the light receiving portions included in the light projecting receiver receives the reflected light by the light projected from the light projecting portions of all the plurality of light emitting and receiving devices.

According to the above configuration, the optical safety sensor measures the distance to the object in the monitoring area by a plurality of light emitting and receiving devices, so that normal monitoring is performed even if any one of the light receiving and receiving devices malfunctions. Can be continued. Further, by comparing the distance measurement results of each light emitting / receiving device, it is possible to detect a problem in any one of the light emitting / receiving devices. Further, since a commercially available module operating in the TOF method can be used as a light projecting receiver, the optical safety sensor is inexpensive as compared with the configuration described in Patent Document 1 using the reference floodlight and the reference receiver dedicated to the self-test. Can be realized.

Furthermore, since it is possible to receive the light projected from one light emitting and receiving device with the other light receiving and receiving device, the light projecting part and the light receiving part of each light emitting and receiving device are diagnosed when a problem occurs, and an abnormal part is detected. Can be identified.

The optical safety sensor according to the one aspect is further provided with one or more groups composed of a plurality of light emitting / receiving devices different from the group consisting of the plurality of light emitting / receiving devices, and the target monitoring areas of each group are different. The distance measuring unit may sequentially switch the groups to measure the distance, and the detecting unit may sequentially switch the groups to detect the abnormality. According to this configuration, it is possible to perform distance measurement and abnormality diagnosis by one distance measuring unit and a detecting unit for abnormality diagnosis of a light emitting / receiving device included in a plurality of groups having different monitoring areas. Therefore, by sharing the distance measuring unit and the detecting unit, it is possible to safely monitor a wider area while keeping the equipment cost low.

In the optical safety sensor according to the one side surface, the detection unit is the first light projector from the light projecting unit of the first light emitting and receiving device, which is one of the plurality of light emitting and receiving devices. From the measurement distance based on the time until the light reception by the light receiving unit of the 1 light receiving device and the light projected by the light projecting unit of the second light receiving device different from the first light receiving device, the second light receiving and receiving is performed. Even if it is determined that an abnormality has occurred in either the first light emitting receiver or the second light receiving receiver when the measurement distance based on the time until the light receiving by the light receiving portion of the device does not match. Good. According to this configuration, either the first throwing receiver or the second throwing receiver is abnormal by comparing the measurement distances of the first throwing receiver and the second throwing receiver based on the time from the projection to the light reception. Can be determined whether or not is occurring.

In the optical safety sensor according to the one side surface, the detection unit determines the time from the light projection by the light projection unit of the first light emitting / receiving device to the light reception by the light receiving unit of the first light emitting / receiving device. When the measurement distance based on the measurement distance does not match the measurement distance based on the time from the light projected by the light projecting unit of the second light emitting receiver to the light receiving by the light receiving unit of the first light receiving device, the said It may be configured to determine that an abnormality has occurred in either the light projecting portion of the first light emitting / receiving device or the light projecting unit of the second light emitting / receiving device. According to this configuration, a plurality of different light projecting units perform whether or not an abnormality has occurred in at least one of the light projecting unit of the first light emitting and receiving device and the light projecting unit of the second light emitting and receiving device. It can be determined by comparing the measurement distances based on the time until the specific light receiving unit receives the light.

In the optical safety sensor according to the one side surface, the detection unit indicates that an abnormality has occurred in either the light projecting unit of the first light emitting / receiving device or the light projecting unit of the second light emitting / receiving device. When the determination is made, it is based on the time from the light projected by the light projecting unit of the first light emitting receiver to the light receiving by the light receiving unit of the first light receiving device, which was started at the first time T = 0. When the measurement distance and the light projection by the light projecting unit of the first light emitting / receiving device are started after the time ΔT from the first time T = 0, the light emitting device of the first light emitting / receiving device is started from the first time T = 0. When the difference between the light receiving unit and the measurement distance based on the time until the light is received is different from the distance difference ΔS based on the time ΔT, it is said that an abnormality has occurred in the light emitting unit of the first light emitting / receiving device. A measurement distance based on the time from the light projected by the light projecting unit of the second light emitting receiver to the light receiving by the light receiving unit of the first light receiving device, which is determined and started at the first time T = 0. When the light projection by the light projecting unit of the second light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving light of the first light emitting / receiving device is started from the first time T = 0. When the difference between the measurement distance and the measurement distance based on the time to receive the light received by the unit is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light emitting unit of the second light emitting receiver. You may. According to this configuration, the presence or absence of an abnormality in the light projecting portion of the first light projecting receiver and the second light receiving light are used by using the difference in the measurement distance based on the time from each of the two light projections with a time interval to the light reception. The presence or absence of an abnormality in the light projecting part of the vessel can be individually determined.

In the optical safety sensor according to the one side surface, the detection unit determines the time from the light projection by the light projection unit of the first light emitting / receiving device to the light reception by the light receiving unit of the first light emitting / receiving device. When the measurement distance based on the measurement distance and the measurement distance based on the time from the light projection by the light projecting unit of the first light emitting / receiving device to the light receiving by the light receiving unit of the second light receiving device do not match, the measurement distance is described. It may be determined that an abnormality has occurred in either the light receiving portion of the first light receiving receiver or the light receiving portion of the second light receiving receiver. According to this configuration, whether or not an abnormality has occurred in at least one of the light receiving part of the first light emitting and receiving unit and the light receiving part of the second light emitting and receiving unit is determined by different projections of the specific light emitting parts. It can be determined by comparing the measurement distances based on the time until each light receiving unit receives light.

In the optical safety sensor according to the one side surface, the detection unit determines that an abnormality has occurred in either the light receiving unit of the first light receiving device or the light receiving part of the second light receiving device. In this case, the measurement distance based on the time from the projection by the light projecting unit of the first light emitting / receiving device started at the first time T = 0 to the light receiving by the light receiving unit of the first light emitting / receiving device. When the light projection by the light projecting unit of the first light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving light of the first light emitting / receiving device is started from the first time T = 0. When the difference between the measurement distance and the measurement distance based on the time to receive the light received by the unit is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light receiving unit of the first throwing receiver. The measurement distance based on the time from the light projected by the light projecting unit of the first light emitting receiver to the light receiving by the light receiving unit of the second light receiving device, which was started at the first time T = 0, and the above. When the projection by the light projecting unit of the first light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving unit of the second light emitting / receiving device starts from the first time T = 0. When the difference from the measurement distance based on the time until light reception is different from the distance difference ΔS based on the time ΔT, it may be determined that an abnormality has occurred in the light receiving portion of the second throwing light receiver. According to this configuration, the presence or absence of an abnormality in the light receiving portion of the first light receiving device and the second light receiving device are used by using the difference in the measurement distance based on the time from each of the two light projections with a time interval to the light reception. It is possible to determine the presence or absence of an abnormality in the light receiving portion of the above.

In the optical safety sensor according to the one side surface, the detection result in the detection unit forming one set with the first light emitting / receiving device is mutual with the detection result in another detecting unit forming one set with the second light emitting / receiving device. If they are compared and the detection results are different from each other, an error may be output. According to this configuration, the detection result of the first throwing receiver and the detection result of the second throwing receiver can be compared with each other. If the detection results are different from each other, it is considered that an abnormality has occurred in at least one of the detection results. In such a case, it is possible to determine the presence or absence of the abnormality with higher accuracy by outputting an error. it can.

According to one aspect of the present invention, an optical safety sensor can be realized at low cost.

It is a block diagram which shows an example of the main part structure of the optical safety sensor which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows an example of the application situation of the optical safety sensor which concerns on the application example of this invention. It is a time chart which shows an example of the control of the light projection performed by the first light emitting / receiving device at the time of abnormality diagnosis in the optical safety sensor 1 according to the first embodiment of the present invention, and (a) is the light projection at the first time T = 0. (B) indicates that the next light projection was started after the time ΔT from the first time T = 0. It is a flowchart which shows an example of the flow of the diagnostic process executed by the optical safety sensor which concerns on Embodiment 1 of this invention. It is a flowchart which shows an example of the flow of the process which the optical safety sensor which concerns on Embodiment 1 of this invention executes in the abnormality diagnosis process. It is a flowchart which shows an example of the flow of the process which the optical safety sensor which concerns on Embodiment 1 of this invention executes in the light-emitting part diagnostic process. It is a flowchart which shows an example of the flow of the process which the optical safety sensor which concerns on Embodiment 1 of this invention executes in the light receiving part diagnostic process.

§1 Application example First, an example of a situation in which the present invention is applied will be described with reference to FIG. FIG. 2 schematically illustrates an example of an application scene of the optical safety sensor 1 according to the present embodiment. In the optical safety sensor 1 according to the present embodiment, an area including a work range in which the robot arm 100 works is set as a monitoring area, and a user who has invaded the supervised viewing area is prevented from colliding with the robot arm 100. Used.

As shown in FIG. 2, the optical safety sensor 1 monitors an area including the working range of the robot arm 100 as a monitoring area. When the optical safety sensor 1 detects that an object has entered the monitoring area from the change in the distance measured by the TOF method, the optical safety sensor 1 transmits the detection result to the robot arm 100. When the robot arm 100 receives the detection result from the optical safety sensor 1, the robot arm 100 decelerates or stops its operation so that the objects do not collide with each other.

The optical safety sensor 1 includes at least two light emitting and receiving devices that project light into the same monitoring area and receive the reflected light from the monitoring area. The optical safety sensor 1 determines the presence or absence of an abnormality based on the distance to the monitoring area calculated by the first light emitting / receiving device 20A and the second light receiving / receiving device 20B of the at least two light receiving / receiving devices. When the optical safety sensor 1 determines that an abnormality has occurred, it diagnoses the content of the abnormality. Specifically, the optical safety sensor 1 executes the next projection from at least one of the first projection receiver 20A and the second projection receiver 20B after a lapse of a certain period of time, and the next projection and the next projection thereof. The abnormal part is identified based on the distance from the received reflected light to the measured monitoring area. The optical safety sensor 1 transmits a diagnosis result to the robot arm 100, and the robot arm 100 operates according to the diagnosis result. For example, the specified abnormal portion of the optical safety sensor 1 may be output using an output device such as an operation panel of the robot arm 100.

The optical safety sensor 1 can measure the distance to the monitoring area and the object invading the monitoring area by the TOF method using at least two light emitting / receiving devices. Then, in the optical safety sensor 1, the light projection and the light reception can be shared and executed between the first light emitting and receiving device 20A and the second light receiving and receiving device 20B. Thereby, for example, it is possible to check whether or not there is an abnormality in the light projection and light reception in each light emitting / receiving device, and if an abnormality occurs, it is possible to identify the location where the abnormality has occurred. Further, since a commercially available module that operates in the TOF method can be used as a light projecting receiver, the optical safety sensor 1 can be compared with the configuration described in Patent Document 1 using the reference floodlight and the reference receiver dedicated to the self-test. It can be realized at low cost. Therefore, it is possible to realize an inexpensive and highly safe optical safety sensor 1 that suppresses an abnormality in monitoring the monitoring area due to an abnormality in the light receiving / receiving device.

§2 Configuration Example Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1, 3 to 7.

(Configuration of optical safety sensor)
The outline and configuration of the optical safety sensor 1 according to one aspect of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an example of a main configuration of the optical safety sensor 1. The optical safety sensor 1 includes a first output unit 10A, a second output unit 10B, a first light emitting / receiving device 20A, a second light emitting / receiving device 20B, a first evaluation unit 30A, and a second evaluation unit 30B. The first light emitting / receiving device 20A and the second light emitting / receiving device 20B include the same light projecting unit 21 and the light receiving unit 22, and the first evaluation unit 30A and the second evaluation unit 30B have the same ranging unit 31 and the same ranging unit 30B. The detection unit 32 is provided. In the optical safety sensor 1, one light emitting / receiving device forms one set with the corresponding evaluation unit and output unit. In the illustrated example, the first throwing receiver 20A forms one pair with the first evaluation unit 30A and the first output section 10A, and the second throwing receiver 20B is the second evaluation unit 30B and the second output section 10B. And one pair.

The optical safety sensor 1 can operate the first throwing receiver 20A and the second throwing receiver 20B according to the instructions of the first evaluation unit 30A and the second evaluation unit 30B. The optical safety sensor 1 operates by being attached to the robot arm 100 as a part of the robot arm 100 shown in FIG. 2, for example.

The first output unit 10A outputs the information received from the first evaluation unit 30A, and the second output unit 10B outputs the information received from the second evaluation unit 30B. For example, the first output unit 10A obtains the diagnosis result of the abnormality diagnosis performed by the first evaluation unit 30A on at least one of the first throwing receiver 20A and the second throwing receiver 20B from the first evaluation unit 30A. Get it and output it to the outside. The first output unit 10A and the second output unit 10B may be indicators that notify the content of the information received from each evaluation unit by blinking the LED or the like.

The first throwing receiver 20A and the second throwing receiver 20B are modules that operate according to the instructions of the first evaluation unit 30A and the second evaluation unit 30B. Specifically, the light projecting unit 21 projects light onto the monitoring area, and the light receiving unit 22 receives the reflected light reflected in the monitoring area. The first light emitting / receiving device 20A and the second light emitting / receiving device 20B transmit information regarding the light projecting and light receiving by themselves to the first evaluation unit 30A and the second evaluation unit 30B. In the illustrated example, the first light emitting / receiving device 20A and the second light emitting / receiving device 20B are configured to have the same light projecting unit 21 and the light receiving unit 22, but are provided with different light emitting units and light receiving units. There may be.

In the illustrated example, the light first emitter and receiver 20A is projected into the monitoring area with a light projecting portion 21 and T _A, the reflected light received from the monitoring area and R _A using the light receiving portion 22. Similarly, the light second emitter and receiver 20B is projected on the monitored area using a light projecting portion 21 and T _B, the reflected light received from the monitoring area and R _B with a light receiving portion 22. Note that the R _A contains reflected light to T _B, similarly noted that the R _B might include the reflected light to T _A.

The first evaluation unit 30A and the second evaluation unit 30B collectively control each part of the optical safety sensor 1. Each of the first evaluation unit 30A and the second evaluation unit 30B uses the distance measuring unit 31 to operate the first light emitting / receiving device 20A and the second light emitting / receiving device 20B, respectively, and the optical safety sensor 1 is obtained from the data obtained. Calculate (measure) the measurement distance from to the monitoring area. Then, the detection unit 32 performs an abnormality diagnosis based on the measurement result. Further, the first evaluation unit 30A and the second evaluation unit 30B can transmit and receive information as needed. For example, when the light receiving unit 22 of the second light emitting / receiving device 20B receives the reflected light of the light projecting unit 21 of the first light emitting / receiving device 20A, the first evaluation unit 30A emits the second light from the second evaluation unit 30B. Information regarding the light reception of the light receiver 20B may be acquired. Conversely, the second evaluation unit 30B may acquire information regarding the light projection of the first light emitting / receiving device 20A from the first evaluation unit 30A. Then, the first evaluation unit 30A and the second evaluation unit 30B form a pair with the second throwing receiver 20B for the detection result (diagnosis result) in the detection unit 32 forming one pair with the first throwing receiver 20A. Mutual comparison is made with the detection result in the detection unit 32. That is, the first evaluation unit 30A and the second evaluation unit 30B perform the same abnormality diagnosis for one combination of light projection and light reception, and determine whether or not there is a failure in the evaluation unit by comparing the diagnosis results. If the diagnosis results are the same in the mutual comparison, the first evaluation unit 30A and the second evaluation unit 30B transmit and output the diagnosis results to the first output unit 10A and the second output unit 10B, respectively. On the other hand, when the diagnosis results are different from each other, an error is transmitted to each of the first output unit 10A and the second output unit 10B to output the error.

The distance measuring unit 31 measures the distance to the object in the monitoring area by using the time required from the light emission to the light reception. Specifically, when the distance measuring unit 31 receives information on light projection and light reception from at least one of the first light emitting / receiving device 20A and the second light receiving / receiving device 20B, the distance measuring unit 31 uses the received information from the optical safety sensor 1. Calculate the measurement distance to the monitoring area. The ranging unit 31 may receive information regarding light projection and light reception via an evaluation unit different from the evaluation unit including itself. Light projecting portion 21 of the first emitter and receiver 20A is projected light T _A, consider a case where the reflected light R _A relative-projecting light receiving portion 22 of the first emitter and receiver 20A receives. In this case, the distance measuring unit 31, by using the time t and the speed of light c from the light projecting of the start time of the optical T _A to the start time of the receiving of the reflected light R _A, from the optical safety sensors 1 to the monitoring area Calculate the distance S. In the following explanation,
S = R (T)
Indicates the distance from the optical safety sensor 1 to the monitoring area, which is calculated by using the start time of the projection of the light T and the start time of the reception of the reflected light R. That is, the light projecting portion 21 of the first emitter and receiver 20A is projected light T _A, the distance measuring unit 31 when the light receiving unit 22 has received the first emitter and receiver 20A the reflected light R _A relative-projecting light Is
S ₌ R A _(T A)
Is calculated. Further, the distance measuring unit 31 of the first evaluation unit 30A and the distance measuring unit 31 of the second evaluation unit 30B calculate the measurement distance for one combination of light projection and light reception, respectively. Then, the distance measuring unit 31 of the first evaluation unit 30A transmits the calculated distance to the detection unit 32 of the first evaluation unit 30A, and the distance measuring unit 31 of the second evaluation unit 30B detects the second evaluation unit 30B. The calculated distance is transmitted to the unit 32.

The detection unit 32 detects an abnormality occurring in either the first light emitting / receiving device 20A or the second light emitting / receiving device 20B based on the measurement result by the distance measuring unit 31. More specifically, the detection unit 32 is a combination of various combinations of the light projecting unit 21 and the light receiving unit 22 included in the first light emitting / receiving device 20A and the light projecting unit 21 and the light receiving unit 22 included in the second light emitting / receiving device 20B. The distance measuring unit 31 compares a plurality of distances measured by the distance measuring unit 31 to detect an abnormality. The comparison of a plurality of distances is performed by both the detection unit 32 of the first evaluation unit 30A and the detection unit 32 of the second evaluation unit 30B, respectively.

(Abnormal diagnosis by controlling the projection timing)
A method in which the optical safety sensor 1 according to the present embodiment controls the projection timing to perform an abnormality diagnosis will be described with reference to FIG. FIG. 3 is a time chart showing an example of light projection control performed by the first light emitting / receiving device 20A at the time of abnormality diagnosis in the optical safety sensor 1. FIG. 3A shows that the projection was started at the first time T = 0, and FIG. 3B shows that the next projection was started after the time ΔT from the first time T = 0. ..

As shown in FIG. 3A, the first light emitting / receiving device 20A uses the light projecting unit 21 to start light projecting based on the light projecting signal at the first time T = 0. At the same time as the light projection, the first light emitting / receiving device 20A receives the reflected light for the light projection using the light receiving unit 22, and detects it as a light receiving signal. Depending on the distance between the optical safety sensor 1 and the monitoring area, the timing at which the received signal is started to be detected is delayed from the first time T = 0. In the illustrated example, the light receiving unit 22 of the first light emitting / receiving device 20A starts receiving light at _{time T = t 1.} The optical safety sensor 1 is based on the time from the first time T = 0 when the light projection is started to the time T = t ₁ when the reflected light for the light projection is first detected as a received signal by the distance measuring unit 31. calculates the distance S ₁ between the optical safety sensors 1 and the monitoring area.

As shown in FIG. 3B, after FIG. 3A, the first light emitting / receiving device 20A uses the light projecting unit 21 to project light based on the light projecting signal after the first time T = 0 and the time ΔT. Start the light. It is preferable that ΔT is a value very small with respect to the flight time of light, and may be several nanoseconds, for example. In FIG. 3B, since the light projection start time changes with respect to FIG. 3A, the light reception start time also changes to _{time T = t 2.} By an optical safety sensor 1 is distance measuring unit 31, based on the time from the first time T = 0 to time T = t ₂ was detected reflected light to the first as a light receiving signal for the light projecting optical safety sensors 1 calculating the distance S ₂ between the monitoring area and.

Thereafter, the detection unit 32 of the optical safety sensors 1, the distance difference between the S ₁ and the distance S ₂ may determine whether equal to the distance difference ΔS based on the time [Delta] T, equal the first light projecting and receiving It is determined that no abnormality has occurred in the light emitting unit 21 and the light receiving unit 22 of the device 20A. That detection unit 32, when an abnormality in any of the light projecting portion 21 and the light receiving portion 22 of the first emitter and receiver 20A is generated, the difference between the distance S ₁ and the distance S ₂ by the abnormal , The determination is made by utilizing the fact that the theoretical distance difference ΔS based on the time ΔT does not match.

In the above description, the light projecting unit 21 and the light receiving unit 22 of the first light emitting / receiving device 20A are used, but it goes without saying that the light emitting unit 21 and the light receiving unit 22 may be in any combination. The optical safety sensor 1 applies the above-mentioned method to some combinations relating to the light emitting unit 21 and the light receiving unit 22 to identify a location where an abnormality has occurred.

(Flow of diagnostic processing)
The flow of the diagnostic process executed by the optical safety sensor 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing an example of the flow of the diagnostic process executed by the optical safety sensor 1.

First, the first evaluation unit 30A instructs the first light emitting / receiving device 20A to project light. The first emitters and receivers 20A that has received the instruction, the projecting light optical T _A to the monitoring area using the light projecting unit 21, receives the reflected light R _A relative-projecting light by the light receiving unit 22. The first light emitting / receiving device 20A transmits data including a light emitting start time and a light receiving start time to the ranging unit 31 of the first evaluation unit 30A. Distance measuring unit 31 receives the data from the first emitter and receiver 20A, the first emitter and receiver 20A by using the time required to receive light from the start of the projection distance R _{A (T A)} Is calculated (S1). Distance measuring unit 31 transmits the calculated distance _R A a _{(T A)} to the detection unit 32.

Next, the second evaluation unit 30B instructs the second light emitting / receiving device 20B to emit light. The second emitters and receivers 20B which has received the instruction, the projecting light optical T _B to the monitoring area using the light projecting unit 21 is received by the light receiving unit 22 a reflected light R _B for-projecting light. The second light emitting / receiving device 20B transmits data including a light emitting start time and a light receiving start time to the ranging unit 31 of the second evaluation unit 30B. Distance measuring unit 31 receives the data from the second emitter and receiver 20B, the second emitter and receiver 20B by using the time required to receive light from the start of the projection distance R _{B (T B)} Is calculated (S2). Distance measuring unit 31 transmits the calculated distance _R B a _{(T B)} in the detection portion 32.

Then, the detection portion 32 of the first evaluation unit 30A and the second evaluation unit 30B, the distance _R A distance measuring unit 31 calculates the first evaluation unit 30A _{(T A)} is, the distance measuring section of the second evaluation unit 30B 31 is equal to or equality with the calculated distance _{R B (T B) (S3} ). If it is determined that they are equal (YES in S3), the detection unit 32 determines that there is no problem in monitoring the monitoring area. After that, the optical safety sensor 1 ends a series of processes.

On the other hand, when the distance _{R A (T} A) is not equal to the distance _{R B (T} B) in S3 (NO in S3), the detection unit 32 error of the first evaluation unit 30A and the second evaluation unit 30B Output (S4). Then, the optical safety sensor 1 executes an abnormality diagnosis process described later (S5). After executing the abnormality diagnosis process, the optical safety sensor 1 ends a series of processes.

(Abnormal diagnosis processing)
The flow of the abnormality diagnosis process executed by the optical safety sensor 1 according to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing an example of the flow of the abnormality diagnosis process executed by the optical safety sensor 1.

First, the optical safety sensor 1 executes a light projecting unit diagnostic process described later, and whether or not an abnormality has occurred in the light projecting unit 21 included in each of the first light emitting receiver 20A and the second light emitting receiver 20B. Is diagnosed (S11).

After that, the optical safety sensor 1 executes a light receiving unit diagnostic process described later to diagnose whether or not an abnormality has occurred in the light receiving unit 22 included in each of the first light receiving receiver 20A and the second light receiving receiver 20B. (S12).

Then, the detection unit 32 of the first evaluation unit 30A and the second evaluation unit 30B collects the diagnosis results in each of the light emitting unit diagnostic processing (S11) and the light receiving unit diagnostic processing (S12). After that, the detection unit 32 outputs the collected results to the first output unit 10A and the second output unit 10B (S13). After that, the process transitions to the caller of the abnormality diagnosis process.

(Diagnosis processing of floodlight)
The flow of the light projecting unit diagnostic process executed by the optical safety sensor 1 according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing an example of the flow of the light projecting unit diagnostic process executed by the optical safety sensor 1.

First, perform the S1 and the same processing in FIG. 4, and calculates the distance _{R A (T} A). That is, the first emitter and receiver 20A that has received the light projecting instruction from the first evaluation unit 30A includes a light T _A is projected, receives the reflected light R _A relative-projecting light. The first light emitting / receiving device 20A transmits data including a light emitting start time and a light receiving start time to the ranging unit 31 of the first evaluation unit 30A. When the ranging unit 31 of the first evaluation unit 30A receives data from the first light emitting / receiving device 20A, the measurement distance _RA (measurement distance RA based on the time from the start of the first light emitting / receiving device 20A to the light receiving light) ( T _a) to calculate the (S21).

Next, the second evaluation unit 30B instructs the second light emitting / receiving device 20B to emit light. The second emitters and receivers 20B which has received the instruction for projecting light optical T _B to the monitoring area. Then, the first light emitting / receiving device 20A receives the reflected light _RA at the light receiving unit 22. The ranging unit 31 of the first evaluation unit 30A acquires the start time of light projection from the second light emitting / receiving device 20B via the second evaluation unit 30B, and acquires the start time of light reception from the first light emitting / receiving device 20A. .. Then, the distance measuring unit 31 of the first evaluation unit 30A is the optical _{T B} by the light-projecting portion 21 of the second emitter and receiver 20B from the light projecting, of the reflected light _{R A} by the light receiving portion 22 of the first emitter and receiver 20A calculating the measured distance _R a based on time until receiving _{(T B)} (S22).

After S22, the detection portion 32 of the first evaluation unit 30A determines whether to match the distance calculated in S21 _{R A (T} A) distance calculated in _{S22 R A (T B) (} S23). If it is determined that they match (YES in S23), the detection unit 32 determines that no abnormality has occurred in the light projecting unit 21 of the first light emitting / receiving device 20A and the light emitting unit 21 of the second light emitting / receiving device 20B. After that, the process proceeds to S30.

On the other hand, when the distance _{R A (T} A) is determined not to match the distance _R A _{(T B)} in S23 (NO in S23), the detection unit 32, light projecting portion 21 of the first emitter and receiver 20A and the second 2 It is determined that an abnormality has occurred in at least one of the light projecting units 21 of the light projecting receiver 20B. Then, in the first evaluation unit 30A, the time when the light projecting unit 21 of the first light emitting / receiving device 20A starts projecting light in S21 is set to the first time T = 0, and after the first time T = 0 and the time ΔT. The first light emitting / receiving device 20A is instructed to start the light projecting again. The first emitters and receivers 20A receiving the instruction for projecting light optical T _A to the monitoring area. Then, the first light emitting / receiving device 20A receives the reflected light _RA at the light receiving unit 22. Distance measuring unit 31 of the first evaluation unit 30A calculates the measured distance _{R A (T} A) based on the time to receive light from the first time T = 0 (S24).

Then, the detection portion 32 of the first evaluation unit 30A, the difference _{R A} of the calculated distance _R A _{(T A),} and the calculated measured distance _R A _{(T A)} with the projecting light after the time ΔT in S21 It is determined whether (ΔT) matches the distance difference ΔS based on the time ΔT (S25). _RA (ΔT) is calculated by the method described with reference to FIG. When _{it is determined that RA} (ΔT) matches ΔS (YES in S25), the detection unit 32 determines that no abnormality has occurred in the light projecting unit 21 of the first light emitting / receiving device 20A, and the process proceeds to S27. .. On the other hand, _{when it is determined that RA} (ΔT) does not match ΔS (NO in S25), the detection unit 32 determines that an abnormality has occurred in the light emitting unit 21 of the first light emitting / receiving device 20A (S26). .. After that, the process proceeds to S27.

In S27, the second evaluation unit 30B sets the time when the light projecting unit 21 of the second light emitting / receiving device 20B starts projecting light in S22 as the first time T = 0, and the time ΔT from the first time T = 0. Later, the second light emitting / receiving device 20B is instructed to start the light projecting again. The second emitters and receivers 20B which has received the instruction for projecting light optical T _B to the monitoring area. Then, the first light emitting / receiving device 20A receives the reflected light _RA at the light receiving unit 22. The distance measuring unit 31 of the first evaluation unit 30A is a measurement distance based on the time from when the second light emitting / receiving device 20B starts projecting light after the time ΔT until the first light emitting / receiving device 20A receives light, as in S22. R _{a (T B)} is calculated (S27).

Then, the detection portion 32 of the first evaluation unit 30A, the difference between the calculated distance _R A _{(T B),} and the measured distance _R A based on time to receive light from the light projecting after time [Delta] T _{(T B)} in S22 It _{is determined whether or not RA} (ΔT) coincides with the distance difference ΔS based on the time ΔT (S28). When _{it is determined that RA} (ΔT) matches ΔS (YES in S28), the detection unit 32 determines that no abnormality has occurred in the light projecting unit 21 of the second light emitting / receiving device 20B. After that, the optical safety sensor 1 ends the light projecting unit diagnostic process, and transitions to the caller of the light projecting unit diagnostic process with the diagnosis results up to this point. On the other hand, _{when it is determined that RA} (ΔT) does not match ΔS (NO in S28), the detection unit 32 determines that an abnormality has occurred in the light emitting unit 21 of the second light emitting / receiving device 20B (S29). .. After that, the process proceeds to S30.

In S30, the second evaluation unit 30B executes the same processing as that executed by the first evaluation unit 30A in S21 to S29, and the light projecting unit 21 and the second light emitting / receiving device 20B of the first light emitting / receiving device 20A are subjected to the same processing. An abnormality diagnosis is performed on the light projecting unit 21 (S30). That is, the measurement second evaluation unit 30B compares calculates two measurement distance R _{A (T A)} and R _{A (T B),} if no match calculated using the projection after time ΔT The distance _RA (ΔT) is compared with the distance difference ΔS. Then, from the comparison result, the second evaluation unit 30B determines whether or not an abnormality has occurred in the light projecting unit 21 of the first light emitting / receiving device 20A and the light projecting unit 21 of the second light emitting / receiving device 20B. After that, the first evaluation unit 30A and the second evaluation unit 30B determine whether or not the result diagnosed by the first evaluation unit 30A by the processing of S21 to S29 matches the result diagnosed by the second evaluation unit 30B in S30. Judgment (S31). If it is determined that they match (YES in S31), the optical safety sensor 1 ends the light projecting unit diagnostic process, and transitions to the caller of the light projecting unit diagnostic process with the diagnosis results up to this point. On the other hand, when it is determined that they do not match (NO in S31), the optical sensor 1 sets an error indicating that the location where the abnormality has occurred is unknown (S32), and transitions to the caller of the light projecting unit diagnostic process. To do.

The light received and received by the first evaluation unit 30A for diagnosis and the light received and received by the second evaluation unit 30B for diagnosis are the same. In other words, the first evaluation unit 30A and the second evaluation unit 30B execute the processing of S21 to S29 and the processing of S30 at the same timing, respectively. Then, in S31, the diagnosis results in each evaluation unit are compared. As a result, the optical safety sensor 1 can perform an abnormality diagnosis on the light projecting unit with higher accuracy than a configuration having one evaluation unit.

(Receiver diagnostic processing)
The flow of the light receiving portion diagnostic process executed by the optical safety sensor 1 according to the present embodiment will be described with reference to FIG. 7. FIG. 7 is a flowchart showing an example of the flow of the light receiving unit diagnostic process executed by the optical safety sensor 1.

First executes the same processing as S1 in FIG. 4, and calculates the distance _{R A (T A) (S41} ). Next, the first evaluation unit 30A instructs the first light emitting / receiving device 20A to project light. The first emitters and receivers 20A receiving the instruction for projecting light optical T _A to the monitoring area. The second emitter and receiver 20B is to receive the reflected light _{R B} by the light receiving unit 22. The ranging unit 31 of the first evaluation unit 30A acquires the start time of light projection from the first light emitting / receiving device 20A, and acquires the start time of light reception from the second light emitting / receiving device 20B via the second evaluation unit 30B. .. Then, the distance measuring unit 31, from the light projecting optical T _A by the light projector 21 of the first emitter and receiver 20A, based on the time until receiving the reflected light R _B by the light receiving portion 22 of the second emitter and receiver 20B measured distance _R B _{(T a)} to calculate the (S42).

After S42, the detection portion 32 of the first evaluation unit 30A determines whether the distance _R A calculated in S41 _{(T A)} matches the calculated distance _R B _{(T A)} in S42 (S43). If it is determined that they match (YES in S43), the detection unit 32 determines that no abnormality has occurred in the light receiving unit 22 of the first light emitting / receiving device 20A and the light receiving unit 22 of the second light receiving / receiving device 20B. After that, the process proceeds to S50.

On the other hand, when the distance _{R A (T} A) is determined not to match the distance _R B _{(T A)} in S43 (NO in S43), the detection unit 32, the first emitter and receiver 20A receiving portion 22 and the second It is determined that an abnormality has occurred in at least one of the light receiving units 22 of the light emitting / receiving device 20B. Then, in the first evaluation unit 30A, the time when the light projecting unit 21 of the first light emitting / receiving device 20A starts projecting light in S41 is set to the first time T = 0, and after the first time T = 0 and the time ΔT. The first light emitting / receiving device 20A is instructed to start the light projecting again. The first emitters and receivers 20A receiving the instruction for projecting light optical T _A to the monitoring area. Then, the first light emitting / receiving device 20A receives the reflected light _RA at the light receiving unit 22. Distance measuring unit 31 of the first evaluation unit 30A includes a first emitter and receiver 20A calculates the measured distance based on the time until the light receiving from the start of the projection _{R A (T} A) after a time [Delta] T (S44).

Then, the detection portion 32 of the first evaluation unit 30A, the difference between the calculated distance _R A _{(T A),} and the measured distance _R A based on time to receive light from the light projecting after time [Delta] T _{(T A)} S41: It _{is determined whether or not RA} (ΔT) coincides with the distance difference ΔS based on the time ΔT (S45). When _{it is determined that RA} (ΔT) matches ΔS (YES in S45), the detection unit 32 determines that no abnormality has occurred in the light receiving unit 22 of the first throwing light receiver 20A, and the process proceeds to S47. On the other hand, _{when it is determined that RA} (ΔT) does not match ΔS (NO in S45), the detection unit 32 determines that an abnormality has occurred in the light receiving unit 22 of the first throwing receiver 20A (S46). After that, the process proceeds to S47.

In S47, the first evaluation unit 30A sets the time when the light projecting unit 21 of the first light emitting / receiving device 20A starts projecting light in S42 as the first time T = 0, and the time ΔT from the first time T = 0. Later, the first light emitting / receiving device 20A is instructed to start the light projecting again. The first emitters and receivers 20A receiving the instruction for projecting light optical T _A to the monitoring area. The second emitter and receiver 20B is to receive the reflected light _{R B} by the light receiving unit 22. Distance measuring unit 31 of the first evaluation unit 30A, the measurement distance R _{B (T A} based on the time from the first emitter and receiver 20A is to start projection after a time ΔT to the second emitter and receiver 20B is received ) Is calculated (S47).

Then, the detection portion 32 of the first evaluation unit 30A, the difference between the calculated distance _R B _{(T A),} the measured distance _R B based on time to receive light from the light projecting after time ΔT and _{(T A)} in S42 R _B ([Delta] T) determines whether or not to match the distance difference ΔS based on the time [Delta] T (S48). If it is determined that R _B ([Delta] T) is consistent with [Delta] S (YES at S48), the detection unit 32 determines that no abnormality occurs in the light receiving portion 22 of the second emitter and receiver 20B. After that, the process proceeds to S50. On the other hand, it is determined that if it is determined that _{R B} ([Delta] T) does not match the [Delta] S (NO at S48), the detection unit 32 is abnormality in the light receiving portion 22 of the second emitter and receiver 20B has occurred (S49). After that, the process proceeds to S50.

In S50, the second evaluation unit 30B executes the same processing as that executed by the first evaluation unit 30A in S41 to S49, and receives light from the light receiving unit 22 of the first light receiving device 20A and the light receiving light from the second light receiving device 20B. An abnormality diagnosis is performed on the part 22 (S50). That is, the measurement second evaluation unit 30B compares calculates two measurement distance R _{A (T A)} and R _{B (T A),} if no match calculated using the projection after time ΔT The distance _RA (ΔT) is compared with the distance difference ΔS. Then, from the comparison result, the second evaluation unit 30B determines whether or not an abnormality has occurred in the light receiving portion 22 of the first throwing receiver 20A and the light receiving portion 22 of the second throwing receiver 20B. After that, the first evaluation unit 30A and the second evaluation unit 30B determine whether or not the result diagnosed by the first evaluation unit 30A by the processing of S41 to S49 matches the result diagnosed by the second evaluation unit 30B in S50. Judgment (S51). If it is determined that they match (YES in S51), the optical safety sensor 1 ends the light receiving unit diagnostic process, and transitions to the caller of the light receiving unit diagnostic process with the diagnosis results up to this point. On the other hand, when it is determined that they do not match (NO in S51), the optical sensor 1 sets an error indicating that the location where the abnormality has occurred is unknown (S52), and transitions to the caller of the light projecting unit diagnostic process. To do.

The light received and received by the first evaluation unit 30A for diagnosis and the light received and received by the second evaluation unit 30B for diagnosis are the same. In other words, the first evaluation unit 30A and the second evaluation unit 30B execute the processing of S41 to S49 and the processing of S50 at the same timing, respectively. Then, in S51, the diagnosis results in each evaluation unit are compared. As a result, the optical safety sensor 1 can perform abnormality diagnosis on the light receiving unit with higher accuracy than the configuration in which one evaluation unit is used.

Through the above processing, the optical safety sensor 1 can detect when any one of the light emitting and receiving devices has a defect by comparing the distance measurement results of the respective light emitting and receiving devices. Further, since a commercially available module operating in the TOF method can be used as a light projecting receiver, the optical safety sensor is inexpensive as compared with the configuration described in Patent Document 1 using the reference floodlight and the reference receiver dedicated to the self-test. Can be realized.

Furthermore, since it is possible to receive the light projected from one light emitting and receiving device with the other light receiving and receiving device, the light projecting part and the light receiving part of each light emitting and receiving device are diagnosed when a problem occurs, and an abnormal part is detected. Can be identified. Furthermore, the accuracy of the diagnosis result can be improved by comparing the results of the abnormality diagnosis performed for each evaluation unit.

[Modification example]
In the above configuration example, the optical safety sensor 1 is configured to include only one group consisting of the first throwing receiver 20A and the second throwing receiver 20B. However, for example, it may be configured to include a plurality of light emitting / receiving devices different from this group, and further include one or more groups whose monitoring target is an area different from the monitoring area monitored by this group. That is, a plurality of light emitting and receiving receivers may be connected to the first evaluation unit 30A and the second evaluation unit 30B in order to monitor a plurality of areas. However, it is necessary that the second evaluation unit 30B can also monitor each of the plurality of areas monitored by the first evaluation unit 30A. In this case, the first evaluation unit 30A and the second evaluation unit 30B sequentially switch the group of the light emitting / receiving receivers that monitor the same area to measure the distance and perform the abnormality diagnosis. Specifically, the distance measuring unit 31 may sequentially switch each group to measure the distance for each monitoring area, and the detection unit 32 may sequentially switch each group to detect an abnormality for each group. .. Then, the first evaluation unit 30A and the second evaluation unit 30B may output the measurement distance or the like by using the first output unit 10A and the second output unit 10B.

[Summary]
The optical safety sensor (1) according to the first aspect of the present invention includes a light projecting unit (21) that projects light into the monitoring area and a light receiving unit (22) that receives the reflected light from the monitoring area. The distance to the object in the monitoring area is measured by using the plurality of light emitting and receiving receivers (first light emitting and receiving device 20A, second light receiving and receiving device 20B) and the time required from the light projection to the light receiving. A plurality of distance measuring units (31) and a plurality of detecting units (32) for detecting an abnormality occurring in any of the plurality of light emitting / receiving devices based on the measurement result by the distance measuring unit are provided. One light emitting / receiving device forms one pair with one corresponding distance measuring unit and one detecting unit, and each of the light receiving units included in the plurality of light emitting / receiving units is of all the plurality of light receiving / receiving units. The configuration is such that the reflected light generated by the light projected from the light projecting unit is received.

According to the above configuration, since the distance to the object in the monitoring area is measured by a plurality of light emitting and receiving devices, normal monitoring can be continued even if any one of the light receiving and receiving devices malfunctions. .. Further, by comparing the distance measurement results of each light emitting / receiving device, it is possible to detect a problem in any one of the light emitting / receiving devices. Further, since a commercially available module operating in the TOF method can be used as a light projecting receiver, the optical safety sensor is inexpensive as compared with the configuration described in Patent Document 1 using the reference floodlight and the reference receiver dedicated to the self-test. Can be realized.

Furthermore, since it is possible to receive the light projected from one light emitting and receiving device with the other light receiving and receiving device, the light projecting part and the light receiving part of each light emitting and receiving device are diagnosed when a problem occurs, and an abnormal part is detected. Can be identified.

The optical safety sensor (1) according to the second aspect of the present invention has a plurality of optical safety sensors (1) different from the group consisting of the plurality of light emitting and receiving receivers (first light receiving and receiving device 20A, second light receiving and receiving device 20B) in the first aspect. One or more groups consisting of light emitting and receiving receivers are further provided, and the target monitoring areas of each group are different. The distance measuring unit (31) sequentially switches between the groups to measure the distance, and at the same time, the distance is measured. The detection unit (32) may be configured to sequentially switch between the groups to detect the abnormality.

According to the above configuration, it is possible to perform distance measurement and abnormality diagnosis by one distance measuring unit and a detecting unit for abnormality diagnosis of a light emitting / receiving device included in a plurality of groups having different monitoring areas. Therefore, by sharing the distance measuring unit and the detecting unit, it is possible to safely monitor a wider area while keeping the equipment cost low.

In the optical safety sensor (1) according to the third aspect of the present invention, in the first or second aspect, the detection unit (32) has the plurality of light emitting / receiving devices (first light emitting / receiving device 20A, second light receiving device). From the light projected by the light projecting unit (21) of the first light emitting and receiving device (20A), which is one of the light receiving receivers (20B), the light received by the light receiving unit (22) of the first light emitting and receiving device. From the measurement distance based on the time to, and the light projected by the light projecting unit (21) of the second light emitting / receiving device (20B) different from the first light receiving device, the light receiving unit of the second light emitting / receiving device. When the measurement distance based on the time until the light reception according to (22) does not match, it may be determined that an abnormality has occurred in either the first light receiver or the second light receiver. ..

According to the above configuration, either the first throwing receiver or the second throwing receiver can be selected by comparing the measurement distances of the first throwing receiver and the second throwing receiver based on the time from the light projection to the light receiving. It is possible to determine whether or not an abnormality has occurred.

In the optical safety sensor (1) according to the fourth aspect of the present invention, in the third aspect, the detection unit (32) is the light projecting by the light projecting unit (21) of the first light emitting / receiving device (20A). From the measurement distance based on the time until the light reception by the light receiving unit (22) of the first light receiving device and the light projected by the light projecting unit (21) of the second light receiving device (20B). When the measurement distance based on the time until the light reception by the light receiving unit of the first light receiving device does not match, the light projecting unit of the first light receiving device and the light projecting unit of the second light receiving device. It may be configured to determine that an abnormality has occurred in any of the above.

According to the above configuration, a plurality of light projecting units different from each other determine whether or not an abnormality has occurred in at least one of the light projecting unit of the first light emitting and receiving device and the light projecting unit of the second light emitting and receiving device. It can be determined by comparing the measurement distances based on the time until the specific light receiving unit receives the emitted light.

The optical safety sensor (1) according to the fifth aspect of the present invention is the light projecting unit (21) of the first light emitting / receiving device (20A) and the light emitting / receiving unit (20B) of the second light emitting / receiving device (20B) in the fourth aspect. When it is determined that an abnormality has occurred in any of the light projecting units (21), the detection unit (32) determines that the light projecting of the first light emitting / receiving device started at the first time T = 0. The measurement distance based on the time from the light projected by the unit to the light received by the light receiving unit (22) of the first light receiving unit, and the first light emitting / receiving device after the time ΔT from the first time T = 0. The difference between the measurement distance based on the time from the first time T = 0 to the light reception by the light receiving unit of the first light receiving device when the light projecting by the light projecting unit is started is the time ΔT. When it is different from the distance difference ΔS based on the above, it is determined that an abnormality has occurred in the light projecting portion of the first light emitting / receiving device, and the light projecting of the second light emitting / receiving device started at the first time T = 0. The measurement distance based on the time from the light projected by the light unit to the light received by the light receiving unit (22) of the first light receiving unit, and the second light receiving device after the time ΔT from the first time T = 0. The difference between the measurement distance based on the time from the first time T = 0 to the light reception by the light receiving unit of the first light receiving device when the light projecting by the light emitting unit is started is the time. If it is different from the distance difference ΔS based on ΔT, it may be determined that an abnormality has occurred in the light projecting portion of the second light emitting / receiving device.

According to the above configuration, the presence or absence of an abnormality in the light projecting portion of the first light projecting receiver and the second light emitting device are used to determine the presence or absence of an abnormality in the light projecting section of the first light emitting and receiving device, using the difference in the measurement distance based on the time from each of the two light projections with a time interval to the light reception. The presence or absence of an abnormality in the light projecting portion of the receiver can be individually determined.

In the optical safety sensor (1) according to the sixth aspect of the present invention, in any one of the third to fifth aspects, the detection unit (32) is the light projecting unit (21) of the first light emitting / receiving device (20A). ) To the light reception by the light receiving unit (22) of the first light receiving device, and the light projected by the light projecting unit of the first light receiving device. When the measurement distance based on the time until the light reception by the light receiving unit (22) of the second light receiving device (20B) does not match, the light receiving part of the first light receiving device and the second light receiving device of the second light receiving device. It may be configured to determine that an abnormality has occurred in any of the light receiving units.

According to the above configuration, whether or not an abnormality has occurred in at least one of the light receiving part of the first light emitting and receiving unit and the light receiving part of the second light emitting and receiving unit is different from each other in the light emitting part of the specific light emitting part. It can be determined by comparing the measurement distances based on the time until light is received by each of the plurality of light receiving units.

In the optical safety sensor (1) according to the seventh aspect of the present invention, in the sixth aspect, the detection unit (32) is the light receiving part (22) of the first light receiving device (20A) and the second light receiving part (22). When it is determined that an abnormality has occurred in any of the light receiving parts (22) of the light receiving device (20B), the light emitting part (the light emitting part of the first light emitting and receiving device) started at the first time T = 0. The measurement distance based on the time from the light projected by 21) to the light received by the light receiving portion of the first light receiving device, and the light projected by the first light receiving device after the time ΔT from the first time T = 0. The difference between the measurement distance based on the time from the first time T = 0 to the light reception by the light receiving unit of the first light receiving device when the light projection by the optical unit is started is based on the time ΔT. When it is different from the distance difference ΔS, it is determined that an abnormality has occurred in the light receiving portion of the first light emitting / receiving device, and the light projecting unit of the first light emitting / receiving device started at the first time T = 0. The measurement distance from the light projector to the light reception by the light receiving unit of the second light receiving device and the light projecting unit of the first light emitting and receiving device after the time ΔT from the first time T = 0. The difference between the first time T = 0 and the measured distance based on the time from the light receiving portion of the second light receiving receiver to the light reception when the light projection is started is the distance difference ΔS based on the time ΔT. If it is different from the above, it may be determined that an abnormality has occurred in the light receiving portion of the second light emitting / receiving device.

According to the above configuration, the presence or absence of an abnormality in the light receiving portion of the first light receiving device and the second light receiving light are used by using the difference in the measurement distance based on the time from each of the two light projections with a time interval to the light reception. It is possible to determine the presence or absence of an abnormality in the light receiving portion of the device.

The optical safety sensor (1) according to the eighth aspect of the present invention detects the detection result in the detection unit (32) forming a pair with the first light emitting / receiving device (20A) in any one of the third to seventh aspects. It may be configured to mutually compare with the detection results of another detection unit (32) forming one set with the second light emitting / receiving device (20B) and output an error if the detection results are different from each other.

According to the above configuration, the detection result of the first throwing receiver and the detection result of the second throwing receiver can be compared with each other. If the detection results are different from each other, it is considered that an abnormality has occurred in at least one of the detection results. In such a case, it is possible to determine the presence or absence of the abnormality with higher accuracy by outputting an error. it can.

[Example of realization by software]
The control block (particularly the distance measuring unit 31 and the detecting unit 32) of the optical safety sensor 1 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or by software. You may.

In the latter case, the optical safety sensor 1 includes a computer that executes a program instruction, which is software that realizes each function. The computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. Then, in the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium", for example, a ROM (Read Only Memory) or the like, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) for expanding the above program may be further provided. Further, the program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. In addition, one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1 Optical safety sensor 20A 1st light emitting / receiving device (light emitting / receiving unit)
20B 2nd light emitting / receiving device (light receiving / receiving unit)
21 Light projecting unit 22 Light receiving unit 31 Distance measuring unit 32 Detection unit

Claims (8)

A plurality of light emitting and receiving devices including a light projecting unit that projects light into the monitoring area and a light receiving unit that receives the reflected light from the monitoring area.
A plurality of distance measuring units that measure the distance to an object in the monitoring area using the time required from the light projection to the light reception.
It is provided with a plurality of detection units for detecting an abnormality occurring in any of the plurality of light emitting / receiving devices based on the measurement result by the distance measuring unit.
One light emitting and receiving device forms a pair with one corresponding distance measuring unit and one detecting unit.
Each of the light receiving portions included in the plurality of light receiving receivers receives the reflected light due to the light projected from the light projecting portions of all the plurality of light emitting and receiving devices .
The detection unit receives light from the light projected by the light projecting unit of the first light emitting and receiving device, which is one of the plurality of light receiving and receiving devices, by the light receiving unit of the first light emitting and receiving device. The measurement distance based on the time until, and the time from the light projected by the light projecting unit of the second light receiving device different from the first light receiving device to the light receiving by the light receiving unit of the second light receiving device. When the measurement distances based on the above do not match, it is determined that an abnormality has occurred in either the light projecting portion of the first light emitting / receiving device or the light projecting unit of the second light emitting / receiving device. Optical safety sensor. When the detection unit determines that an abnormality has occurred in either the light projecting unit of the first light emitting / receiving device or the light projecting unit of the second light emitting / receiving device, the detection unit determines that an abnormality has occurred.
The measurement distance based on the time from the light projected by the light projecting unit of the first light emitting / receiving device to the light receiving by the light receiving unit of the first light emitting / receiving device started at the first time T = 0, and the above. When the projection by the light projecting unit of the first light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving unit of the first light emitting / receiving device starts from the first time T = 0. When the difference from the measurement distance based on the time to receive light is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light projecting portion of the first light receiving receiver.
The measurement distance based on the time from the light projected by the light projecting unit of the second light emitting receiver to the light receiving by the light receiving unit of the first light receiving device, which was started at the first time T = 0, and the above. When the projection by the light projecting unit of the second light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving unit of the first light emitting / receiving device starts the light projecting from the first time T = 0. When the difference from the measurement distance based on the time to receive light is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light projecting portion of the second light emitting receiver. The optical safety sensor according to claim 1. The detection unit includes a measurement distance based on the time from the light projected by the light projecting unit of the first light receiving device to the light receiving by the light receiving unit of the first light receiving device, and the first light receiving device. When the measurement distance based on the time from the light projected by the light projecting unit to the light receiving by the light receiving unit of the second light receiving unit does not match, the light receiving unit of the first light emitting and receiving device and the light receiving unit. The optical safety sensor according to claim 1 or 2 , wherein it is determined that an abnormality has occurred in any of the light receiving portions of the second light emitting / receiving device. A plurality of light emitting and receiving devices including a light projecting unit that projects light into the monitoring area and a light receiving unit that receives the reflected light from the monitoring area.
A plurality of distance measuring units that measure the distance to an object in the monitoring area using the time required from the light projection to the light reception.
It is provided with a plurality of detection units for detecting an abnormality occurring in any of the plurality of light emitting / receiving devices based on the measurement result by the distance measuring unit.
One light emitting and receiving device forms a pair with one corresponding distance measuring unit and one detecting unit.
Each of the light receiving portions included in the plurality of light receiving receivers receives the reflected light due to the light projected from the light projecting portions of all the plurality of light emitting and receiving devices.
The detection unit receives light from the light projected by the light projecting unit of the first light emitting and receiving device, which is one of the plurality of light receiving and receiving devices, by the light receiving unit of the first light receiving device. The measurement distance based on the time until, and the time from the light projected by the light projecting unit of the second light receiving device different from the first light receiving device to the light receiving by the light receiving unit of the second light receiving device. When the measurement distances based on the above do not match, it is determined that an abnormality has occurred in either the light receiving portion of the first light emitting / receiving device or the light receiving unit of the second light receiving / receiving device. Optical safety sensor. When the detection unit determines that an abnormality has occurred in either the light receiving unit of the first light receiving device or the light receiving part of the second light receiving device, the detection unit determines that an abnormality has occurred.
The measurement distance based on the time from the light projected by the light projecting unit of the first light emitting / receiving device to the light receiving by the light receiving unit of the first light emitting / receiving device started at the first time T = 0, and the above. When the projection by the light projecting unit of the first light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving unit of the first light emitting / receiving device starts from the first time T = 0. When the difference from the measurement distance based on the time to receive light is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light receiving portion of the first throwing light receiver.
The measurement distance based on the time from the light projected by the light projecting unit of the first light emitting receiver to the light receiving by the light receiving unit of the second light receiving device, which was started at the first time T = 0, and the above. When the projection by the light projecting unit of the first light emitting / receiving device is started after the time ΔT from the first time T = 0, the light receiving unit of the second light emitting / receiving device starts from the first time T = 0. When the difference from the measurement distance based on the time until light reception is different from the distance difference ΔS based on the time ΔT, it is determined that an abnormality has occurred in the light receiving portion of the second throwing light receiver. The optical safety sensor according to claim 3 or 4. The detection result in the detection unit forming one set with the first throwing receiver is compared with the detection result in another detecting unit forming one set with the second throwing receiver, and if the detection results are different from each other, an error occurs. The optical safety sensor according to any one of claims 1 to 5 , characterized in that A plurality of light emitting and receiving devices including a light projecting unit that projects light into the monitoring area and a light receiving unit that receives the reflected light from the monitoring area.
A plurality of distance measuring units that measure the distance to an object in the monitoring area using the time required from the light projection to the light reception.
It is provided with a plurality of detection units for detecting an abnormality occurring in any of the plurality of light emitting / receiving devices based on the measurement result by the distance measuring unit.
One light emitting and receiving device forms a pair with one corresponding distance measuring unit and one detecting unit.
Each of the light receiving portions included in the plurality of light receiving receivers receives the reflected light due to the light projected from the light projecting portions of all the plurality of light emitting and receiving devices.
The detection unit receives light from the light projected by the light projecting unit of the first light emitting and receiving device, which is one of the plurality of light receiving and receiving devices, by the light receiving unit of the first light receiving device. The measurement distance based on the time until, and the time from the light projected by the light projecting unit of the second light receiving device different from the first light receiving device to the light receiving by the light receiving unit of the second light receiving device. If the measurement distances based on the above do not match, it is determined that an abnormality has occurred in either the first light emitting / receiving device or the second light receiving / receiving device.
The detection result in the detection unit forming one set with the first throwing receiver is compared with the detection result in another detecting unit forming one set with the second throwing receiver, and if the detection results are different from each other, an error occurs. An optical safety sensor characterized by outputting. A group consisting of a plurality of light emitting and receiving devices different from the group consisting of the plurality of light receiving and receiving devices is further provided, and the target monitoring area of each group is different.
The distance measuring unit sequentially switches between the groups to measure the distance, and at the same time,
The optical safety sensor according to any one of claims 1 to 7, wherein the detection unit sequentially switches between the groups to detect the abnormality.

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